Unfortunately it's a matter of trial and erro to find out which code works. TV's are a bit like android phones, there are so may different models from the same manufacturers that there isn't a fit all solution.
You can also try this method, but it entails another lot of key presses. Click on Home > Help and Settings > Help > Set up Remote. Follow instructions there it should give you a series of codes to try. If they don't work you can also put 0999 in place of the code and press channel up until the TV turns off, then press OK.
The Service you do for others is the rent you pay for your room here on Earth - Muhammad Ali
I've tried the 0999 method and it doesn't work. I need the correct number. I have tried to find an email address to contact Virgin customer service but don't think they exist. No one manning the phones either. Must be the worst customer services of any company anywhere.